Stylus feed mechanism for sound recorders



Nov. 11, 1941. J, H, REBOLD 2,262,299

STYLUS FEED MECHANISM FOR SOUND RECORDERS Filed Jan. 15, 1941 2 Sheets-Sheei 1 FIG: I

25 H- 6 5 1a f 1 FIG 2 l| E -:I o\ l 8 26 H n -u k 1 x /3/////// A INVENTOR Nov. 11, 1941. J. H. REBOLD STYLUS FEED MECHANISM FOR SOUND RECORDERS Filed Jan. 15, 1941 2 Sheets-Sheet 2 FIG. 6'

lNl/ENTOR Patented Nov. 11, 1941 UNITED STATES PATENT OFFICE STYLUS FEED MECHANISM FOR SOUND RECORDERS 20 Claims.

The present application is a continuation-inpart of my pending application, Serial #344,107, filed July 5, 1940.

This invention relates to stylus feeding mechanism for sound recorders, and more particularly to disc sound recorders in which a stylus is fed radially across a revolving blank record disc upon which the stylus engraves or cmbosses a phonic groove representative of the sound being recorded. Such mechanisms have long been known to the art, but in general require comparatively bulky and expensive apparatus for satisfactory operation. It is believed that a simple, inexpensive and compact feed mechanism would contribute greatly to the expansion of the recorder market, especially in the home recording field.

Accordingly, the main object of this invention is to provide a simple and compact, low cost feed mechanism requiring a minimum of parts.

Another object of this invention is to provide a simple means of changing the direction of stylus feed from outside-in to inside-out without substitution of parts, said means requiring only a simple transposition of part of the feed mechanism.

A further object of this invention is to provide means for automatic release of the feeding action at the limits of the desired stylus travel.

Another object of this invention is to provide an overhead feed mechanism of such compactness .as to allow it to be conveniently folded back against the stylus-carrying arm when the feed mechanism is not in use.

A further object of this invention is to provide an under-turntable feed mechanism with means for manually releasing the stylus-carrying arm from the feed mechanism when it is desired to use the arm for playback of records.

Another object of this invention is to provide a eed mechanism which automatically releases its control of the stylus-carrying arm when the turntable ceases to rotate, thus allowing the stylus "to be manually shifted to any desired position in its path without requiring the raising of the stylus-carrying arm other than a slight raising of the stylus to clear the record blank.

A further object of this invention is to provide a feed mechanism free from backlash and freeplay of the stylus, and including damping means resisting spurious movements due to imperfections and irregularities in the record blank.

Still another object of this invention is to provide simple means of varying the feed-pitch or distance between grooves, without substitution of parts.

An additional object of this invention is to provide for intermittent feed of the stylus, a portion of each turntable revolution actuating the feed mechanism, the remainder of the turntable revolution not resulting in any feed of the stylus.

Still other objects and advantages of this invention will be apparent from the specification, and the drawings, in which:

Fig. l is a partial plan view of a recording turntable and feed mechanism constructed according to one form of my invention, the dotted lines indicating how the feed mechanism may be folded back and locked against the stylus-carrying arm when not in use.

Fig. 2 is a vertical sectional view taken upon line 2-2 of Fig. 1, showing the general features of the overhead feed mechanism.

Fig. 3 is an enlarged vertical sectional view taken upon line 33 of Fig. 2, and shows the details of the feeding head.

Fig. 4 is an enlarged sectional view taken upon line l4 of Fig. 3, and most clearly illustrates the principle of operation.

Fig. 5 is a vertical front view of a recording turntable, stylus-carrying arm, and under-turntable feed mechanism constructed according to my invention, the stylus-carrying arm being shown in its off position, clear of the turntable.

Fig. 6 is a plan view with the turntable removed and the stylus-carrying arm sectioned on line B6 of Fig. 5, the dotted lines indicating the limits of feed-bar and slide-rod movement.

Fig. '7 is an enlarged vertical sectional view taken upon line .l--l of Fig. 6, and shows the details of the under-turntable feeding head.

Fig. 8 is a partial side view of the rear portion of the stylus-carrying arm showing in solid lines .the arm manually raised out of contact with the feed-bar, and in dotted lines, the arm lowered into feeding engagement with the feed-bar.

Fig. 9 is illustrative of an alternative form of slide-rod and corresponding feed mechanism.

Similar numerals refer to similar parts throughout the description and the different views.

The baseboard. l is a general representation of a frame, upon which is mounted the bearing 2, in which turns the shaft 3, to which is attached the turntable 4, carrying the blank record 5, upon which the phonic groove representing the recorded sound is to be impressed. The turntable is driven at suitable recording speed by any of the methods well known to the art, such as gear drive to the shaft, friction roller drive to the turntable rim, etc.

For overhead feed, the shaft 3 has a radial cam surface 6 cut at its upper end and extending downward to a point a short distance above the record blank, leaving a portion I of the usual diameter to serve as centering pin for the record blank 5, and also for the feeding head 8. At its upper end the shaft has a tapered portion 9, to allow easy positioning of the feeding head 8 and the cam follower I0. Cam follower I is so bent that it exerts a substantially constant clamping pressure on the cam surface 6 at two opposite tangential contacts II and I2 (Fig. 4), and has an enlarged end portion I3 which is pierced by a hole somewhat larger in diameter than the slide rod I 4. When shaft 3 is turning in the clockwise direction as indicated, portion I3 of cam follower I0 contacts slide rod I4 at points I5 and I6, forming an angle of approximately 70 degrees between the flat portion of cam follower I0 and the axis of slide rod I4. Slide rod I4 is pivoted at its outer end to the stylus-carrying arm I1 by a balland-socket joint formed by the enlarged ball-shaped end I8 of the slide rod I4, and

the co-operating socket clip I9 fastened to the stylus-carrying arm I1. An additional clip is fastened to the arm to lock the slide rod I4 against it when the feed mechanism is not in use. The dotted lines of Fig. 1 show the slide rod thus folded back against the arm, the feeding head 8 having been slid back and turned 90 degrees 'any of the well-known electro-mechanical types of transducer capable of converting the electrical undulations representing the sound to be recorded into corresponding vibrations of the erably pivoted for limited vertical movement about the horizontal pivot 24 inside the hollow arm I1, this pivot being so placed with relation to the center of gravity of transducer unit 22 that stylus 23 will have proper weight for recording placed upon it.

Slide rod I4 at the end opposite the styluscarrying arm I! has a split ring 25 sprung into a groove in the rod, thus forming a stop to prevent complete withdrawal of the slide rod from the feeding head 8. The function of feeding head 8 is to form a guide and clamp for the slide rod I4, and to enclose and guide cam follower ID, as well as to properly position both elements about the shaft 3. To this end, the lower portion of feeding head 8 is pierced and upset to form a tubular portion 26 making a slide fit about centering pin I, the upper portion of feeding head 8 being pierced by a hole large enough to clear cam surface 6 without contacting it during any portion of its revolution. The cam follower I0 moves freely within feeding head 8, following the cam surface 6. Feeding head 8 has an elongated lower portion curled up to form portion 21 to substantially enclose and guide the slide rod I4, and is cut away about its center as shown to clear the enlarged portion I3 of the cam follower I0. Curled portion 21 is so formed as to exert a moderate clamping pressure on the slide rod I4, thus preventing back-motion of the latter, as explained more fully below. This clamping pressure is not critical, but may be such that a force of six ounces applied in the direction of slide movement is required to move the slide rod from a position of rest.

The cam surface 6 may be conveniently formed during the machining of the shaft 3, by clamping the shaft in a rotatable jig in such a way that the axis of the shaft is displaced radially from the axis of rotation of the jig by a distance equal to one-half of the distance that the stylus is required to be fed during each revolution of the turntable, or one-half of the feed-pitch. For example, if 100 grooves per inch are required, representing a pitch of 0.01 inch, then the shaft would be offset radially a distance of 0.005 inch -.while the cam. surface is being machined.

The essential mode of operation by which the feeding impulses are imparted to the slide rod is best understood from Fig. 4. It is assumed that :30 about the slide rod axis in order to make a more ,40 recording stylus 23. Transducer unit 22 is prefthe slide rod I4 is to be fed in the left-hand direction (outside-in), and that the shaft 3 rotates in a clockwise direction, as indicated by the arrows. When shaft 3 begins rotating, pressure of cam follower I0 on cam surface 6 at points I I and I2 causes cam follower I D to tend to be swung clockwise until contact is made with slide rod I4 at points I5 and I6. As long as the leading cam surface is advancing, with respect to the axis of rotation, in the left hand direction, enlarged portion I3 of cam follower I0 is locked against slide rod I4, point I5 acting mainly as a pivot, point I6 tending to bite into the slide rod I4 and forming the point of maximum power transfer. In this manner slide rod I4, and with it the stylus-carrying arm I1 and recording stylus 23, is moved ahead through the action of the cam and cam follower during that portion of the shaft revolution that the cam surface is advancing in the direction of required feed.

During the remainder of the shaft revolution, while the cam surface is retreating with respect to the desired direction of feed, cam follower I0 reverses its motion, and being pivoted at point I5, tends to free point I6 from contact with slide rod I4. The locking action is thus released, and enlarged portion I3 then slides back along the slide rod as long as the cam surface is retreating. The damping action of curled portion 21 upon the slide rod I4 is sufiicient to prevent any movement of the slide rod in either direction during this return period, and yet does not prevent forward motion when the feeding action is resumed. There is thus produced an intermittent feed of the stylus, resulting in a record groove which is part spiral and part circular; the transition occurring at the same angular point each rotation.

While the preceding description and the drawings depict a radially displaced circular cam which gives a ratio of feed to no-feed per revolution of one to one, any other desired ratio may be had by appropriate design of the cam.

Should feed in the opposite direction be required (inside-out), the split ring 25 is removed and the slide rod I4 withdrawn from the feeding head 8. Feeding head 8, containing cam follower I0, is then rotated degrees about the axis of shaft 3, slide rod I4 reinserted, and split ring 25 replaced. The slide rod I4 would then appear as if it were below shaft 3 in Fig. 4, and the feeding action would move the slide rod toward the right-hand side.

To reset or adjust the position of the stylus along its feed path, whil the turntable is at rest, it is only necessary to raise the stylus slightstylus-carrying arm may be shifted in either direction by hand. The moment the turntable resumes its rotation, the feeding action is automatically restored as previously detailed. After the recording is completed, the feeding head is raised from the spindle, the slide rod folded back to its position of rest against the side of the stylus-carrying arm, the arm swung clear of the turntable, and the record removed for further processing as required.

Should a concealed or under-turntable feedbe desired, the cam surface may be formed on shaft 3 at a. point such as 28 (Fig. '7) just below the turntable bushing 29. The guide head 30 (corresponding to feeding head 8 previously described in the overhead type of feed) may be U-shaped as shown, the two sides being pierced at opposite points to form a slide fit for slide rod 3|. The right-hand side is further pierced by an elongated slot 32, allowing free passage of the transverse projection 33 on the slide rod 3|. A flat spring 34 is secured to the lower portion of guide head 30, and exerts a pressure of about five ounces against the side of slide rod 3|. The shaft bearing 2 has a short tubular projection 35 raised at its upper end, its outer periphery forming a slide fit with a cooperating hole in the lower portion of guide head 30, and serves to position the guide head 30, the cam follower 36, and the slide rod 3| properly in relation to the cam surface 28. Slide rod 3| has at its inner end a removable L-shaped extension 31, whose purpose is to prevent inadvertent withdrawal of the slide rod from the guide head 30, and also to stop feeding action when its tip contacts the bent portion 38 of cam follower 36. The outer end of slide rod 3| is provided with a forked portion 39 transversely pierced by a hole adapted to receive the connecting pin 40.

The feed bar 4| is pierced by a series of holes 42, 43, 44, adapted to receive the connecting pin 40, and thus provides a ready means of varying the feed-pitch of the stylus. Pivot 45 serves as vertical pivot for both the feed bar 4| and the stylus-carrying arm 46, and may be a rigid post fastened to the base I, while spacing washer 4'! serves to raise the feed bar 4| to its proper height above the base. Where it is desired to raise the arm out of contact with the feed bar, the arm itself is not directly pivoted vertically, but is horizontally pivoted to the U-shaped intermediary link 48, which is in turn vertically pivoted around stud 45. Stylus-carrying arm 46 is further provided with a pair of wing-shaped vertical extensions 49 near its pivoted end, adapted to embrace the feed bar for a portion of its length when the arm is lowered. Wings 49 are provided with a bent portion 50 acting as a stop to limit the descent of arm 46 toward feed bar 4|, and are flared out slightly at their lower extremities to readily position them about the feed bar as the arm descends, yet snugly registering with the feed bar when the stylus-carrying arm is completely lowered.

The cam follower 36 may be formed from a length of strip metal bent into the shape of a U with one leg somewhat longer than the other. The longer leg is pierced near its end by a hole slightly larger than the slide rod 3!, and the bent end 38 is made long enough to extend beyond the edge of guide head 30 so as to allow the stop 31 to contact it when the slide rod is moved to its extreme right-hand position. The width of cam follower 36 is made about one mil less than the width of cam surface 28, so as to allow free transverse motion of the cam follower with re- 'spect to the cam without substantial axial motion. The distance between the legs of the U is made slightly less than the diameter of the cam, so that when the cam follower is in place it will exert a pressure against the cam face at diametrically opposite points. In this way the control of the cam follower 36 over the slide rod 3| is made dependent on the rotation of the shaft 3,, and the feed motion is imparted to the slide rod as previously detailed.

In Fig. 5 and in solid lines in Fig. 6, the styluscarrying arm 46 is shown in registry with the feed bar 4| in its off position clear of the turntable 4. In this position the stop 37 is in contact with the bent portion 38 of the cam follower 36, and the cam follower being thus prevented from making effective two-point contact with the slide rod 3|, no feed of the slide rod can occur, even when the shaft is rotating. The turntable can thus be used for playback of records by means of a separate reproducing arm, in a manner well known to the art.

When it is desired to feed the stylus-carrying arm in making a recording, the arm is moved manually from its position of rest, carrying the feed bar 4| with it, to a suitable point for the stylus 23 to contact the record blank 5. This is done with the turntable at rest. Since stop 31 is no longer in contact with cam follower 33, the feed of the stylus 23 will begin during the first revolution of the turntable, and 'continue until the turntable is stopped, or until the projection 33 on slide :rod 3| comes into contact with the longer end of cam followed 36. When this happens, the feeding action is automatically stopped even though the turntable continues to rotate, since the cam follower 3B is again prevented from making effective two point contact with slide rod 3|. The dotted lines in Fig. 6 indicate this position of slide rod 3| and feed bar 4|. After the recording is completed, the turntable is stopped and the arm carrying with it the feed bar is returned to its position of rest clear of the turntable.

For some applications, it may be desirable to use the same stylus-carrying arm for playback of records, as well as for recording. For this purpose, it is required that the arm be freed from the control of the feed mechanism, so that the reproducing stylus will be free to follow the record grooves. I satisfy this requirement in my invention by using a manually releasable coupling between the stylus-carrying arm 46 and the feed bar 4|. Assuming that the stylus-carrying arm is in its off position clear of the turntable as indicated in Fig. 5, the arm is raised about 20 degrees above the horizontal, assuming the position indicated in solid lines in Fig. 8. The wing portions are then clear of the feed bar, and the arm can then be swung into position over the turntable Without disturbing the feed bar. The arm is now free to follow the record grooves, and since the stop 3l prevents feeding action, f eed bar 4| remains at rest during the turntable rotation for playback.

ress, the slide rod 3!, and with it the feed bar 4!, will continue to be fed inward until stop 33 contacts cam follower 36, after which further feed of these elements will cease. It is thus apparent that no matter where the feed bar 4| may be left, other than its outside off position, it will automatically be carried to its inner limit of travel, and remain there until the arm is manually lowered over it and thus swung to a new recording position or brought back to its outer off position.

Should a change of feed pitch be desired, the connecting pin 40 is removed, the forked portion 39 of slide rod 3| shifted over one of the holes 42, 43, 44 in the feed bar 41, and the connecting pin reinserted. The feed pitch is inversely proportional to the distance between the connecting pin 40 and the pivot 45, a coarser pitch re quiring a smaller distance between these elements.

Although I prefer to use a round slide rod and corresponding feeding elements as previously described, I do not wish to be restricted to this form, as many variations in form are possible within the scope of my invention. Fig. 9 is representative of one such variation of form. In this case, the round slide rod 3| is replaced by the flat slide bar having a closed slot 52 of such dimensions as to allow sliding action across shaft 3 and proper length of feed. The cam follower 53 is formed with a lateral extension 54 slightly wider than the slot 52, and thus exerts an internal clamping action within the slot, as contrasted with the external gripping action on the rod slide first described. The essential mode of operation is substantially the same as previously detailed.

I claim:

1. In a stylus feed mechanism, a rotatable record shaft, a cam rotating directly with said record shaft, an elongated slide member movable lengthwise and passing in proximity to said cam, a cam follower given a reciprocating motion by rotation of said cam and exerting an intermittent gripping action on said slide member, a recording stylus, and means operatively connecting said stylus with said slide member.

2. In a stylus feed mechanism, a rotatable record shaft, a cam rotating directly with said record shaft, an elongated slide member movable lengthwise and passing near said cam, a recording stylus, means connecting said recording stylus with said slide member, and a cam follower cooperating with said cam and exerting an intermittent gripping action on said slide member, said cam follower including a portion exerting spring pressure upon the face of said cam across a plurality of diametrically opposite points, and tending to rotate therewith, whereby the gripping action of said cam follower upon said slide member is made automatically dependent upon the rotation of said record shaft.

3. A stylus feed mechanism, comprising in combination, a rotatable record shaft, a cam driven by said record shaft, a cam follower given a reciprocating motion by the rotation of said cam, a substantially smooth slide rod intermittently gripped by said cam follower, a recording stylus, means connecting said recording stylus with said slide rod, and a member exerting spring pressure against the side of said slide rod, whereby spurious motion of said slide rod and said recording stylus is prevented.

4. In a sound recording machine, a rotatable record shaft, a turntable mounted on said shaft,

a stylus-carrying arm movable about a vertical pivot, a recording stylus carried by said arm, and

means to feed said stylus radially across said turntable, said means comprising a cam rotating with said shaft, an elongated, substantially smooth slide member connected with said arm and passing adjacent said cam, a cam follower given a reciprocating motion by the rotation of said cam and exerting an intermittent gripping action upon said slide member, and a spring member exerting limited pressure against the side of said slide member.

5. In a sound recording machine, a rotatable record shaft, a turntable mounted on said shaft, a stylus-carrying arm movable about a vertical pivot, a recording stylus carried by said arm, and means to feed said stylus radially across said turntable, said means comprising a cam rotating with said shaft, an elongated slide member connected with said arm and passing adjacent said cam, and a cam follower cooperating with said cam and intermittently gripping said slide member, said cam follower exerting spring pressure upon the face of said cam across at least two diametrically opposite points and tending to rotate therewith, thereby making the gripping action of said cam follower upon said slide member automatically dependent upon the rotation of said record shaft.

6. In a sound recording machine, a rotatable record shaft, a turntable mounted on said shaft, a cam rotating with said shaft, a feeding head removably positioned about said cam, a cam follower given a reciprocating motion by the rotation of said cam and guided within said feeding head, an elongated rod member passing through said feeding head and said cam follower, an arm carrying a recording stylus near one end and pivoted for movement about a vertical axis near its other end, a pivot connection between one end of said rod member and the stylus end of said arm, and a clip member fastened to said arm and adapted to yieldably receive a portion of said rod member when said feeding head is manually removed from its position about said cam, and said rod member is turned about its pivot to a position substantially parallel with the axis of said arm.

'7. In a sound recording machine, a rotatable record shaft, a turntable mounted on said shaft, a stylus-carrying arm movable about a vertical pivot, a recording stylus carried by said arm, and means to feed said stylus radially across said turntable, said means comprising a radially eccentric cam formed upon the upper end of said shaft above said turntable, a removable feed head positioned about said cam in spaced relation therewith, an elongated slide member passing through said feed head and in proximate relation to said cam, a pivot connection between said slide member and said arm, and a cam follower positioned within said feed head, said cam follower being formed in substantial U-shape and having an apertured leg through which passes said slide member.

8. In a stylus feed mechanism, a rotatable record shaft, a cam rotating directly with said record shaft, a cam follower exerting spring pressure upon said cam from two sides and tending to rotate therewith, an elongated slide member passing adjacent to said cam and movable lengthwise under the control of said cam follower during the rotation of said cam, a recording stylus, means connecting said stylus with said slide member, and a projecting member connected and traveling with said slide member, adapted to contact a portion of said. cam follower after a predetermined travel of said slide mem ber, whereby said cam follower is automatically prevented from imparting further motion to said slide member.

9. In a sound recording machine, a rotatable record shaft, a turntable mounted on said shaft, a stylus-carrying arm movable about a pivot, a recording stylus, and means to feed said stylus radially across said turntable, said means including a cam rotating with said shaft, a cam follower given a reciprocating motion by the rotation of said cam, an elongated slide member connected with said arm and movable lengthwise past said cam, said cam follower normally exerting an intermittent gripping action upon said slide member during the rotation of said shaft, and a projecting member connected to and traveling with said slide member, adapted to contact a portion of said cam follower after a predetermined travel of said slide member, whereby said cam follower is automatically prevented from further gripping said slide member while said projecting member is in contact with said cam follower.

10. In a sound recording machine, a rotatable record shaft, a turntable mounted on said shaft, a stylus-carrying arm movable in a plane above said turntable about a suitable pivot, a recording stylus carried by said arm, and means to feed said stylus radially across said turntable, said means comprising a cam on said shaft at a point below said turntable, a guide head positioned coaxially with said shaft and in proximity to said cam, an elongated slide member supported by said guide head for lengthwise motion therethrough, a cam follower given a reciprocating motion by the rotation of said cam and intermittently gripping said slide member, a feed bar movable in a plane below said turntable and cooperatively connected with said arm, and a coupling between said slide member and said feed bar, whereby lengthwise movement of said slide member is translated into angular movement of said arm about its pivot.

11. In a sound recording machine, a rotatable record shaft, a turntable mounted on said shaft, a stylus-carrying arm movable in a plane above said turntable about a suitable pivot, a recording stylus carried by said arm, and means to feed said stylus radially across said turntable, said means including a cam on said shaft at a point below said turntable, a feed bar movable in a plane below said turntable and cooperatively connected with said stylus-carrying arm, an elongated slide member linked with said feed bar and movable lengthwise past said cam, and a cam follower exerting spring pressure upon said cam from two opposite sides and tending to rotate therewith, said cam follower exerting an intermittent gripping action upon said slide member during rotation of said shaft.

12. In a sound recording machine, a rotatable record shaft, a turntable mounted on said shaft, a vertically-pivoted arm movable in a horizontal plane above said turntable, an extension connected with said arm and movable in a plane below said turntable, a recording stylus carried by said and means to feed said stylus across said turntable, said means including a cam on said shaft at a point below said turntable, an elongated slide member connected with said extension and passing adjacent said cam, a member exerting spring pressure against said slide member, and a cam follower having an apertured leg through which said slide member is adapted to pass.

13. In a sound recording machine, a rotatable record shaft, feed. means cooperative with said shaft, a feed bar linked with said feed means and movable in one plane about a pivot, a styluscarrying arm movable in one plane substantially parallel with said. first-mentioned plane and in a second plane substantially perpendicular to said first-mentioned plane, means whereby said arm is normally held in cooperative connection with said feed bar, and further means whereby movement of said arm in said' perpendicular plane beyond a. predetermined amount, releases said arm from cooperative connection with said feed bar.

14. In a sound recording and reproducing machine, a rotatable record shaft, feed means cooperative with said shaft, a turntable mounted on said shaft, a pivoted feed bar linked with said feed means and movable under the control of said feed means in a plane below said turntable, a stylus-carrying. arm movable in a plane above said turntable and also in a plane substantially perpendicular to that of said turntable about suitable pivots, and complementary interlocking means on said arm and said feed bar normally holding said arm in cooperative engagement with said feed bar, said last-mentioned means being coextensive for a limited distance in said perpendicular plane, whereby movement of said arm beyond a predetermined amount in said perpendicular plane away from said feed bar will release said arm from cooperative connection with said feed bar.

15. In a sound recording and reproducing machine, a rotatable record shaft, a turntable mounted on said shaft, a cam on said shaft at a point below said turntable, a feed bar movable in a plane below said turntable about a suitable pivot, an elongated slide member linked with said feed bar and passing adjacent said cam, a cam follower, a recording stylus, a stylus-carrying arm movable in a plane above said turntable and also movable in a plane substantially perpendicular to that of said turntable about suitable pivots, and complementary interlocking means on said arm and said feed bar normally holding said arm in cooperative engagement with said feed bar, said means being coextensive for a limited distance in said perpendicular plane, whereby movement of said arm beyond a predetermined amount in said perpendicular plane in a direction away from said feedbar will release said arm from cooperative connection with said feed bar.

16. In a sound recording machine, a rotatable record shaft, a cam on said shaft, an elongated slide member passing in proximity to said cam, a cam follower given a reciprocating motion by the rotation of said cam, and intermittently gripping said slide member, a recording stylus, an elongated pivoted arm connected with said stylus, and releasable coupling means linking said slide member with said arm, said coupling means being adjustable in the direction of the long axis of said arm, whereby the point of linkage may be moved nearer to or further away from the pivot of said arm.

17. In a sound recording machine, a rotatable record shaft, a turntable mounted on said shaft, feed means driven from said shaft, an elongated slide r'nember movable lengthwise under the control of said feed means in a plane below said turntable, a stylus-carrying arm movable, in a plane above said turntable, about a suitable pivot, a recording stylus carried by said arm, an arm-extension operatively connected with said arm and movable about a pivot in a plane below said turntable, and means linking said slide member with said arm-extension, said last mentioned means comprising a coupling member including a coupling pin carried by said slide member, and a plurality of transverse apertures in said armextension adapted to receive said coupling pin, said apertures being spaced in a direction approaching the pivot of said arm-extension, whereby the point of linkage may be manually moved nearer to or further away from said arm-extension pivot.

18. A stylus feed mechanism comprising, in combination, a rotatable record shaft, acam rotating directly with said shaft, a recording stylus, an elongated slide member connected with said stylus and movable lengthwise, a spring member exerting spring pressure against the side of said slide member, and a cam follower cooperating with said cam and exerting an intermittent feeding control over said slide member, said cam follower having a portion exerting spring pressure upon said cam from two opposite sides and tending to rotate therewith.

19. A stylus feed mechanism, comprising in combination, a rotatable record shaft, a cam rotatable by said shaft, a recording stylus, an elongated slide member connected with said stylus and movable lengthwise, a guide head positioned about said shaft in spaced relation to said cam and adapted to guide said slide member, a spring member on said guide head exerting spring pressure against the side of said slide member, and a cam follower cooperating with said cam and exerting an intermittent feeding control over said slide member, said cam follower having a portion exerting spring pressure upon said cam across a plurality of diametrically 0pposite points.

20. A stylus feed mechanism, comprising, in combination, a rotatable record shaft, a cam rotating with said shaft, an elongated slide rod movable lengthwise and passing adjacent to said cam, a recording stylus, means connecting said stylus with said slide rod, a guide head positioned about said shaft in proximity with said cam and adapted to guide said slide rod for lengthwise movement only, and a unitary cam follower and rod-gripping member, said member having a plurality of legs adapted to contact said cam, one of said legs having an aperture through which passes said slide rod.

JACOB H. REBOLD. 

